1. Technical Field
The present invention relates to a powertrain and method for controlling a powertrain in a vehicle.
2. Background Art
To improve fuel economy in vehicles, engines are being downsized. In order to provide sufficient torque to propel the vehicle, many smaller engines are being turbocharged. One issue related to a turbocharged engine is a phenomenon called “turbo lag”. This delay exists because of the time required for the exhaust gases from the engine to accelerate the turbine and then compress the engine intake air. Another way in which vehicle fuel economy is being improved, is through the use of hybrid electric vehicles (HEV's). These vehicles typically utilize a smaller engine in combination with one or more electric machines that can be operated as motors, generators, or both. By combining these two technologies—i.e., turbocharged engines and HEV's—improved fuel economy over conventional vehicles may be realized, while still providing a vehicle that meets the torque requirements of the driver. It would be desirable, however, to provide a turbocharged HEV that did not experience the common problem of turbo lag.